1. Field of the Invention
The present invention relates to a machine and process for magnetically polishing articles which are made of a metal, e.g., gold, silver, platinum, titanium or nickel or a hard plastic material and which have a complicated structure or are desired to be as least deformed by polishing as possible. It relates more particularly to a magnetically-polishing machine and process which can efficiently polish small metal products, e.g., finger rings, finger ring frameworks, slender and thin castings, watch second pointers, shafts, precision instrument parts and false teeth, and hard-plastic products, without deforming edges or complicated parts of the metal and hard-plastic products and without hardening the metals of the metal products and by means of which almost all powdered metal which is formed as a polishing waste can be recovered.
2. Description of the Related Art
Heretofore, precious metal finger rings and finger ring frameworks have been cast by molds and then hand polished. Even a skilled worker can hand polish only about 20 gold finger ring frameworks a day and even fewer when the frameworks are made of platinum, which is harder than gold. On the other hand, polished off powdered precious metal is scattered and, though most of this polished off powdered precious metal is recovered, a part thereof which amounts to about 5-6% of the total of the polished off powdered precious metal is lost. The about 5-6% amount of the polished off powdered precious metal is not negligible in cost.
On the other hand, a barreling machine has polished parts of a machine. Barreling essentially is a process which mechanically agitates polished articles and an abrasive together. When a portion of the abrasive enters recesses defined in the articles being polished that portion of the abrasive no longer can be agitated effectively since it is isolated from the rest of the abrasive.
In addition, the polished articles may collide with each other sufficiently to deform each other. This is especially the case in barreling polished articles each with a complicated and edged configuration. In addition, the barreling entails a drawback that metal pins provided on a barrel strike the metallic articles being polished to harden them.
High-speed polishing a finger ring by means of a polishing machine has been studied. However, since the configuration of the finger ring comprises a combination of irregular delicate curves, the configuration of the finger ring cannot fit a regular motion of the polishing machine, so that the polishing machine excessively and insufficiently polishes various parts of the finger ring. Thus, this high-speed polishing cannot develop delicate inherent curves of the configuration of the finger ring. Consequently, a finger ring has been considered unsuitable for mechanical polishing.